1. Field of the Invention
The present invention relates to an array connector for optical fibers and, more particularly, to such a connector suitable for providing fiber-to-fiber array connections or, alternatively fiber array-to-waveguide connections.
2. Description of the Prior Art
Packaging has become a key issue in evaluating the manufacturability and reliability of optical devices. A significant part of the packaging problem is due to the stringent alignment tolerances required between devices and optical fibers. To date, most applications have required the alignment of only a single fiber. However, with the advent of integrated optical devices, the need has arisen to align linear arrays of fibers to either other arrays of fibers, or an array of waveguides. U.S. Pat. No. 4,217,032 issued to S. K. Sheem on Aug. 12, 1980, discloses one array alignment technique utilizing a two-dimensional intersecting groove pattern and an alignment fiber. U.S. Pat. No. 4,164,363 issued to H. Hsu on Aug. 14, 1979 discloses an alternative technique especially suited for aligning single mode fibers to waveguides. A problem with these and other alignment techniques is the fact that there exist six possible degrees of freedom which must all be aligned. An alternative prior art technique which discloses an arrangement for automatically aligning five of the six possible degrees of freedom is disclosed in U.S. Pat. No. 4,639,074 issued Jan. 27, 1987 to; this inventor and assigned to the same assignee as the present application. As disclosed in this patent, the fiber arrays are held in V-grooves etched in a silicon substrate, where the silicon substrate overlaps the top surface of the mating array. Although this method is useful in achieving array alignment in most applications, it is difficult to employ in situations where polarization maintaining fiber is used, since this particular type of fiber will not necessarily mate and align properly with the V-groove structure.
Polarization maintaining fiber with very low loss and excellent polarization holding ability has been produced by a variety of techniques. One exemplary technique is disclosed in U.S. Pat. No. 4,529,426 issued to W. Pleibel et al on July 16, 1985. As disclosed, high birefringence is introduced into the fiber preform by deforming the preform such that a cladding layer becomes significantly flattened while the core region remains hard and substantially round. Upon being drawn into a fiber, the cladding retains its flattened ellipsoid form as is illustrated in FIGS. 3-5 of Pleibel et al. The availability of this fiber provides significant new potential for optical communication systems, integrated optics and fiber based sensors. In particular, coherent communications systems require control and maintenance of the state of polarization. Therefore, to facilitate the use of polarization maintaining fiber, arrangements for connecting these fibers to waveguides or other devices is required. It is important to note that unlike conventional connectors, axial angular alignment must be maintained so as to properly orient and preserve the state of polarization as it passes through the connection.